1. Field of the Invention
The present invention relates to a resolver, and more particularly to resolution adjustable resolver that can be used in a position feedback system for a rotary motor and can adjust the resolution by arranging the stator and rotor magnetic pole numbers at a specific value.
2. Description of the Prior Art
The working principle of a rotary motor is that the current flows to the stator via a transistor 3-phase inverter and a pulse width modulator (POM), producing a rotating magnetic field, and then the rotating magnetic field will interact with the permanent magnet of the rotor and generate a torque. The intention of an electronic commutator is to enable the stator generated magnetic field to be maintained in a vertical direction with respect t to the magnetic field of the rotor's permanent magnet, so as to produce a maximum torque. And this intention should be achieved by the electronic commutator via a resolver's feedback. In other words, it should precisely detect the position of the rotor's magnetic electrodes and transmit the position signal to the driver, and then the driver gives an instruction to actuate the coil winds of the stator, enabling the stator generated magnetic field to be maintained in a vertical direction with respect t to the magnetic field of the rotor's permanent magnet, thus producing a maximum torque.
As disclosed in U.S. Pat. No. 6,137,204, wherein the magnetic poles of the stator are equidistantly arranged, there is a standard regarding the arrangement of stator with respect to the rotor, and increasing the stator magnetic pole number and the rotor magnetic pole number can increase the resolution. However, such arrangement has the following disadvantages:
1, the method of increasing the resolution by increasing the stator magnetic pole number and the rotor magnetic pole number will have difficulties in coil winding. 2, if want to change such structure into a 2-phase circuit from a phase signal, it requires the use of an extra complicated commutation circuit, and only the 3-above times harmonic wave can be eliminated (only odd harmonic wave is eliminated, excluding the first time fundamental wave).
3, the equidistant arrangement greatly restricts the application of the resolver and wastes too much production time.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.